Air-return dolly



Feb. 18, 1930. J. DITSON ET AL ,1

Y AIR RETURN DOLLY Filed Jan. 1927 I N V EN TOR. A 2f]: 24 rEPefera An Jame z'faon. BY

' HIS AT RNEY.

Patented Feb. 18, 1930 UNITED STATES PATENT OFFICE JESSE DITSON AND ARTHUR E. PETERS, 01? LITTLETON, COLORADO, ASSIGNOR-S TO INGERSOLL-RAND COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY AIR-RETURN DOLLY Application filed January 4, 1927. Serial No. 158,959.

This invention relates to percussive tools, but more particularly to that part of percussive tool known as a dolly for a drill sharpener.

5 The object of this invention is to permit the construction of a drill sharpener dolly in which the well-known dolly return-spring is eliminated. Other objects will be in part obvious and in part pointed out hereinafter. The objects referred to are attained by the mechanism illustrated in the accompany ing drawing, in which Figure 1 is a plan view, partly in longitudinal section, of a dollying tool for a drill. sharpener, and

Figure 2 is a longitudinal sectional elevation of the same implement taken along the line 22 of Figure 1 looking in the direction of the arrows. Referring to the drawing, the drill sharpener tool has a cylinder B, a front head C, and a back head D. The front head C is secured to the cylinder B by bolts E passing through lugs F and G on the front head and cylinder, respectively. Cushioning springs H are placed on the bolts F between lugs G and nuts J. In a similar manner the back head D is separately secured to the cylinder B by bolts K passing through the back head 39 D and through the lugs L on the cylinder B. Cushioning springs O are placed between the back head D and a supporting bar P which is held in place by the heads Q, of the bolts K.

A hammer piston R having an enlarged central portion U and the smaller forwardly and rearwardly extending end portions V and TV, respectively, is reciprocably mount ed in the cylinder B and is caused to deliver blows of impact to a dolly S by pressure fluid admitted to the cylinder B from a source (not shown), the admission of pressure fluid being controlled by a throttle valve T.

A cushioning device is provided to receive the impact of the dolly S on its return stroke. This device consists of a front cylinder washer X having a plurality of helical springs Y seated in pockets Z in the ring X and bearing against a flanged front head bushing 7) extending from the cylinder B into the front head C. The springs Y absorb the shock of the blow delivered by the returning dolly.

The bushing Z) has a flattened tapered seat 0 to receive a correspondingly flattened tapered end portion cl of the dolly S. The seating of the tapered end d of the dolly in the tapered portion 0 of the bushing 12 causes the dolly to be brought inline on its return stroke and to start in true alignment with the work to be operated upon if the dolly S is struck by the hammer piston R. A pin A passing through the bushing b and into the front head C prevents rotation of the bushing 7).

The forward end of the front head C is longitudinally split so that one part 0 may be removed for the purpose of taking the dolly S from the tool. The removable portion e is held securely in place during the operation of the tool by a split ring f drawn tightly together by a bolt 9 which passes through lugs h on the ring 7. The bolt 9 rests in a'groove 7' whereby longitudinal movement of the removable portion e is prevented.

An enlargement is on the rear end of the dolly acts as a piston in a cylinder 0 formed in the front head G and the dolly is withdrawn from the face of a hot steel (not shown) by pressure fluid exerting a force against the enlarged portion is of the dolly S.

In the operation of the tool, pressure fluid is admitted through the throttle valve T and assuming the piston R to be on its rearward stroke as in Figure 2, pressure fluid passes through the passage 19 into the rearward end of the cylinder B, thence through passage (1 and into the forward end of the cylinder B, where the pressure exerted upon the forward face 8 of the enlarged portion U of the piston R forces the piston R rearwardly. At the same time pressure fluid which is admitted to the cylinder 0 by way of a passage 1" forces r the dolly S rearwardly.

Exhaust from the cylinder B takes place when the face 8 of the piston R moves rearwardly far enough to uncover the exhaust port t. When the neck a of piston R opens the port 2), pressure fluid is admitted to the rearward face 'w of the piston R and the piston is driven forward on its working stroke, exhaust taking place when the face w uncovers port If.

The advantages of the above described tool are, among others, the securing of the front and back heads to the cylinder by separate sets of bolts, thus permitting the removal of either front or back head without removing the other, the di iding of the forward part of the front head into two parts permitting the quick removal of the dolly, the device for cushioning the shock of the return stroke of the dolly on the front head parts, and the substitution of fluid pressure for the usual dolly spring.

Ve claim:

1. In a drill sharpener, the combination of a cylinder, a hammer piston in the cylinder, a back head for the cylinder, a front head for the cylinder, a bushing in said front head having a flattened tapered seat, and a dolly adapted to reciprocate in the front head and having a flattened tapered end cooperative with said bushing seat to start said dolly .in alignment with the work to be operated upon.

2. In a drill sharpener, the combination of a cylinder, a hammer piston in the cylinder, a back head for the cylinder, a front head for the cylinder split longitudinally into two parts, a bushing in said front head having a flattened tapered seat and a dolly in the front head adapted to be inserted by separation of the front head parts, and reciprocable in the front head, said dolly being provided with a flattened tapered end cooperating with said bushing seat to start said dolly in alignment with the work to be operated upon, and means to secure the front head parts together.

3. In a drill sharpener the combination of a cylinder, a hammer piston in the cylinder, a back head for the cylinder, a front head for the cylinder, a bushing in said front head, a dolly reciprocable in the front head, and a front cylinder washer resiliently mounted in said cylinder and cooperative with said front head bushing to receive and absorb the shock of said dolly on its return stroke.

i. In a drill sharpener the combination of a cylinder, a hammer piston in the cylinder, a back head for the cylinder, a front head for the cylinder, a bushing in said front head, a dolly reciprocable in the front head, and a front cylinder washer, and coil springs interposed between said washer and said front head bushing to absorb the shock of said dolly on its return stroke.

5. In a drill sharpener the combination of a cylinder, a reciprocatory hammer piston in the cylinder, a washer within said cylinder having a series of pockets to receive cushion springs, a front head secured tosaid cylinder, and a back head separately secured to said cylinder, said front head made in two parts, a split ring and a bolt securing said two parts together, a dolly having an enlarged end within said front head acting as a piston and actuated by motive fluid to withdraw said dolly into said front head, said enlarged end being flattened and tapered and cooperating with a corresponding tapered seat in the front head to start said dolly in alignment with the work to be operated upgn.

6. In a drill sharpener the combination of a cylinder, a hammer piston in the cylinder, a back head for the cylinder, a front head for the cylinder, separate springs and spring bolts for securing said heads independently to the cylinder, said front head being split longitudinally into two parts and provided with a split ring and bolt for'securing said parts together, a dolly having an enlarged piston head reciprocable in said front head and actuated by motive fluid to be withdrawn into said front head, a bushing in said front head having a flattened tapered seat, said dolly head having a. correspondingly flattened tapered portion cooperative with said seat to start said dolly in alignment with the work to be operated upon, a washer in the cylinder having pockets, and cushion springs in said pockets to absorb the shock of the said dolly on its return stroke.

In testimony whereof we have signed this specification.

JESSE DITSON. ARTHUR E. PETERS. 

